1. Field
The disclosure relates to an organometallic compound and organic electroluminescence device employing the same and, more particularly, to a phosphorescent organometallic compound and a phosphorescent organic electroluminescence device employing the same.
2. Description
Recently, with the development and wide application of electronic products, such as mobile phones, PDAs, and notebook computers, there has been increasing demand for flat display elements which consume less electric power and occupy less space. Organic electroluminescent devices are self-emitting and highly luminous, with wide viewing angles, fast response speeds, and simple fabrication methods, making them an industry display of choice.
Generally, an organic electroluminescent device is composed of a light-emission layer sandwiched between a pair of electrodes. When an electric field is applied to the electrodes, the cathode injects electrons into the light-emission layer and the anode injects holes into the light-emission layer. When the electrons recombine with the holes in the light-emission layer, excitons are formed. Recombination of the electron and hole results in light emission.
Depending on the spin states of the hole and electron, the exciton, which results from the recombination of the hole and electron, can have either a triplet or singlet spin state. Luminescence from a singlet exciton results in fluorescence whereas luminescence from a triplet exciton results in phosphorescence. The emissive efficiency of phosphorescence is three times that of fluorescence. Therefore, it is crucial to develop highly efficient phosphorescent material, in order to increase the emissive efficiency of an OLED.
Conventional red phosphorescent materials, however, exhibit lower electroluminescent efficiency, thereby it is difficult to fabricate a high CRI white electroluminescent device by employing conventional red phosphorescent materials. Further, a red light emitted by an OLED is useful for wound healing and thus it the can be utilized for the development of therapeutics for wounds.
Therefore, it is necessary to develop novel organic compounds suitable for red phosphorescent OLEDs to solve the above problems.